Mounting arrangement for a vacuum circuit interrupter



Sept. 8, 1970 w, SHARP 3,527,911

Q MOUNTING ARRANGEMENT FOR A VACUUM CIRCUIT INTERRUPTER Filed July 22, 1968 4 Sheets-Sheet 1 FTgJa J0 N a m I ll T l v I I l 361/ J6- l I J/ I 2*4 a: 9:

- I 60 60 l I .96 .96 I g INVENTOR.

WILL/AM 7. JHA RP BY 5mm A TTOR/VEY 3,527,911 MOUNTINGARRANGEMENT FOR A VACUUM CIRCUIT INTERRUPTER Fild July 22, 1968 w. T. SHARP Sept. 8, 1-970 4 Sheets-Sheet 2 uws/vro/a: WILL/AM I SHARP ATTORNEY Sept. 8, 1970 w.1'. SHARP 3,527,911"

MOUNTING ARRANGEMENT FOR A VACUUM CIRCUIT I NTERRUPTER Filed July 22, 1968 4 Sheets-Sheet 5 INVENTOR. W/LL/AM T SHARP BY 71am ATTORNEY W. T. SHARP Se t. 8, 1970 I MOUNTING ARRANGEMENT'FOR A VACUUM CIRCUIT INTERRUPTER 4 Sheets-Sheet 4 Filed July 22, 1968 IIIIIII/l/I/I/II/III/I/I/Il INVENTO/i: W/LL/AM T SHARP.

ATTORNEY United States Patent Office 3,527,911 Patented Sept. 8, 1970 3,527,911 MOUNTING ARRANGEMENT FOR A VACUUM CIRCUIT INTERRUPTER William T. Sharp, Philadelphia, Pa., assignor to General Electric Company, a corporation of New York Filed July 22, 1968, Ser. No. 746,404 Int. Cl. H01h 33/ 66 U.S. Cl. 200-444 6 Claims ABSTRACT OF THE DISCLOSURE A vacuum type circuit breaker comprises a vacuum interrupter connected between two spaced-apart conductive studs extending transversely of the longitudinal axis of the interrupters tubular envelope. Operating force is supplied to one end of the interrupter via a path that extends transversely of said longitudinal axis. Said one end of the interrupter is substantially rigidly fixed to a supporting framework, but the other end of the interrupter is left unsupported except through the supporting structure at said one end of the interrupter. The stud at said other end of the interrupter is connected to the conductive structure of the interrupter through flexible connecting means that imparts no support to the interrupter.

This invention relates to a mounting arrangement for a vacuum-type circuit interrupter and, more particularly, relates to a mounting arrangement that provides protection against damage to the interrupter from high mechanical forces applied transversely to the longitudinal axis of the interrupter.

In application S.N. 479,373-Darrow et al., filed Aug. 13, 1965 now Pat. No. 3,397,293, and assigned to the assignee of the present invention, there is shown a vacuum-type circuit interrupter connected between two spaced-apart conductive studs extending transversely of the longitudinal axis of the interrupters tubular envelope. The interrupter envelope and the studs are supported generally rigidly on a framework by insulators disposed at opposite ends of the envelope. Operating force is supplied to the interrupter through a linkage partially supported on structure fixed to one end of the envelope. Operation of the linkage produces the desired operation of the interrupter contacts but, in doing so, imparts a force to the interrupter envelope that acts along a path extending transversely of its longitudinal axis.

In working with a circuit breaker of this design, it was found that when the operating force was made relatively high, e.g., over 600 pounds, the life of the interrupter was seriously shortened. The high operating forces were imposing severe loads on the end caps of the interrupter envelope and were producing mechanical failures of these nd caps after a relatively small number of interrupter operations.

An object of the present invention is to protect a vacuum interrupter located in the general environment described hereinabove from being damaged by high forces that might be applied to its end structure transversely of the longitudinal axis of the interrupter envelope.

Another object is to provide the above-described protection to the interrupter against damage from transverse forces and, at the same time, to provide a generally rigid mounting for the conductive studs at opposite ends of the interrupter envelope.

In carrying out my invention in one'form, I provide a framework and a vacuum interrupter comprising a generally tulbular envelope and conducting means forming a conductive path through said envelope when the interrupter is closed. The conducting means comprises a pair of separable contacts and a. conductive rod fixed to one of the contacts for longitudinal movement along the longitudinal axis of the tubular envelope through one end of said envelope. The interrupter is mounted on the framework by means comprising supporting structure fixed to said one end of thetubular envelope and first insulating structure fixed to the supporting structure and to the framework for substantially rigidly securing said one end of the tubular envelope to the framework. The other end of the tubular envelope is substantially unsupported except through said first insulating structure at said one end. A substantial force acting in a direction transverse to said longitudinal axis of the tubular envelope is exerted on said supporting structure during contact operation. A pair of conductive studs are provided at opposite ends of the tubular envelope projecting from the envelope transversely of said longitudinal axis. Means are provided for electrically connecting said pair of studs and said conductive means in the associated vacuum interrupter in series comprising a flexible connection between the portion of said conducting means at the other end of said tubular envelope and the adjacent stud. Second insulating structure is provided for supporting said adjacent stud on said framework.

For a better understanding of the invention reference may be had to the following description taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic side elevational view of a switchgear unit embodying one form of the present invention.

FIG. 1a is a diagrammatic showing of the power circuit in which the switchgear unit of FIG. 1 is connected.

FIG. 2 is an end view of the switchgear unit of FIG. 1 viewed from the front side of the switchgear unit. Certain of the parts inside the switchgear unit are shown in dotted line form and certain others have been omitted for simplicity.

FIG. 3 is a sectional view along the line 3-3 of FIG. 2.

FIG. 4 is an enlarged sectional view along the line 44 of FIG. 3.

FIG. 5 is a plan view of a portion of FIG. 4.

Referring now to FIG. 1, the switchgear unit 9 shown therein comprises a grounded metal cabinet 10 having a top wall 11, a back wall 12, and a bottom wall 13. At each of its laterally opposed sides are sidewalls 14. Extending parallel to the backwell 12 between the sidewalls is a vertically disposed metal partition 16 that is suitably fastened to the walls of the cabinet and is at ground potential. Partition 16 is spaced from the backwall 12 to form a primary conductor compartment 18 between the partition and the backwall.

Located in front of partition 16 is a breaker compartment 20. This breaker compartment 20 is adapted to receive a horizontally-movable circuit breaker unit 24. In FIG. 1, the movable circuit breaker unit 24 is shown completely removed from cabinet 10. In FIG. 3 the movable circuit breaker unit is shown in plan sectional view positioned in its connected position inside the breaker compartment 20 of the cabinet. The movable circuit breaker unit 24 comprises a truck 26 that comprises a base 28 mounted on suitable wheels 29. These wheels roll along the bottom wall of the cabinet when the movable circuit breaker unit is being withdrawn or inserted into its connected position in the cabinet. A more detailed description of the circuit breaker until will soon be presented.

PRIMARY CONDUCTOR COMPARTMENT Located within the primary conductor compartment 18, there are three bus bars 30 constituting the three phases of a three-phase alternating current bus. These three bus bars 30 extend in a horizontal direction across compartment 18 and are disposed in vertically-spaced relationship to each other. As shown in 'FIG. 3, each bus bar 30 extends through the sidewalls 14 of the cabinet via aligned openings 32 provided therein and is partially enclosed by a suitable housing 34.

Each of the bus bars is supported in its illustrated position in a switchgear unit by support means comprising a horizontally-extending stud 36 welded to the bus and a hollow insulator 38 surrounding the stud. Insulator 38 is suitably secured to the stud and is secured to partition 16 through an adapter 40 shown in FIG. 3.

For a more complete description and illustration of this support means, reference may be had to the aforesaid Darrow et al. application.

FIG. la is a schematic diagram of the power circuit through the switchgear unit 9. A purpose of the switchgear unit is to provide a connection between the threephase bus constituted by bus bars 30 and a three-phase line constituted by line conductors 45. When the movable circuit breaker unit 24 is in its connected position depicted in FIG. 1a and is closed, the three line conductors are respectively connected to the three bus bars 30. The line conductors 45 are shown in FIG. 1 extending from line terminals 46 of the switchgear unit toward points outside the switchgear unit.

Each line conductor terminal 46 is constituted by a horizontal-extending stud that extends through the metal partition 16. Each of the studs 46 is supported on partition 16 by a hollow porcelain insulator 38 and an adapter 40 that are substantially the same as the correspondingly designated supporting parts for the bus connected stud 36.

As is shown in the aforesaid Darrow et a1. application (FIG. 5), the bus-connected studs 36 are vertically aligned in a first vertical plane; and the line-connected studs 46 are vertically aligned in a second vertical plane, which is horizontally spaced from the first plane. The line-connected studs 46 are vertically staggered with respect to the bus-connected studs 36.

Referring to FIG. 1, at the free end of each of the studs 36 and 46, a plug-type disconnect contact is provided. These plug-type disconnect contacts 55 are located at the front of the metal partition 16 and are adapted to plug into socket-type disconnect contacts 57 carried by the movable circuit breaker unit 24, when the circuit breaker unit is moved into its connected position of FIG. 3.

MOVABLE CIRCUIT BREAKER UNIT The movable circuit breaker unit 24 comprises three identical vacuum-type circuit interrupters 60'. One of the circuit. interrupters is provided for each phase of the power circuit, as may be clearly seen in the schematic illustration of FIG. 1a. The internal details of the circuit interrupter 60 form no part of the present invention and are therefore shown in schematic form only. For a more specific showing of an interrupter suitable for use in the disclosed circuit breaker, reference may be had to U.S. Pat. 3,163,734-Lee, assigned to the assignee of the present invention. Referring to FIG. 4, generally speaking, the circuit interrupter 60 comprises an evacuated and sealed envelope '62 in which a pair of separable butttype contacts 64 and 66 are mounted. The contacts have been suitably processed to essentially free them of sorbed gases and contaminants. The envelope 62 comprises a tubular housing 67 of insulating material and a pair of end caps 68 and 69 closing off the ends of a tubular housing and suitably sealed thereto. Each of the illustrated end caps comprises a ring 71 of L-shaped cross-section and a plate 7-2 welded to the ring along a joint 73 forming a seal at the outer periphery of the ring and plate. The left-hand contact 64 of FIG. 4 is a stationary contact that is supported on the inner end of a conductive rod The conductive rod projects in sealed relationship through the left hand end of the envelope 62 and is rigidly attached to the end cap 68 as by Welding.

The other contact 66 of the circuit interrupter is a movable contact brazed to the inner end of a conductive actuating rod 76, referred to hereinafter as the movable contact rod. This movable contact rod 76 is mounted for substantially straight-line movement along its longitudinal axis and projects through an opening in the right hand end cap 69. A flexible metallic bellows 78 is interposed between the right hand end cap and the movable contact rod 76 to provide a seal about the contact rod that allows for longitudinal movement thereof without impairing the vacuum inside the envelope 62.

Opening of the circuit interrupter of FIG. 4 is effected by applying a force to the contact rod 76 to drive the movable contact 66 to the right out of engagement with the other contact 64. This moves contact 66 from an engaged position (not shown) to its position illustrated in FIG. 4. Initial separation of the contacts establishes a circuitinterrupting are between the contacts, and this are will persist until about the time a natural current zero is reached. The are will then vanish and be prevented from re-igniting by the high dielectric strength of the vacuum, thus completing the circuit interrupting operation. A tubular shield 77, preferably of metal, surrounds the contacts and condenses the metal vapors resulting from arcing. This shield is suitably supported on casing 67 by a metal disc 77a extending therethrough in sealed relationship.

Closing of the interrupter is effected by driving the right-hand contact 66 of FIG. 4 from its illustrated open position of FIG. 4 leftward into engagement with the other contact '64, thus reestablishing the power circuit through the interrupter.

The actuating means for effecting opening and closing motion of the contact rod 76 will soon be described in some detail, but first a description will be given of the structure that is relied upon for supporting each of the interrupters 60 and for carrying current to and from the interrupters.

The structure upon which the interrupters 60 are sup ported is a framework secured to the base 28- of the truck. Referring to FIG. 3, this framework comprises a pair of rigid metal frames 80 of channel form located at the laterally-opposed sides of the truck 26. Each of these frames 80 is welded at its lower end to the base 28 of truck 26. At vertically-spaced points along their length, each of the frames 80 is welded to horizontally disposed braces 82 that extend toward the front of the truck. Additional vertical frame members 83 are disposed near the front of the truck at its laterally opposed sides, and the horizontally extending braces 82 are suitably welded to these frame members 83. In addition, there is another vertically extending channel 80a forming a part of the framework. This channel 80:: is disposed in an intermediate position between the side braces 82 and is strengthened by suitable transverse braces 84 extending between side braces 82 and channel 80a and welded thereto.

The vacuum interrupters 60 are located between the frame members 80 with the longitudinal axis of each interrupter extending in a horizontal direction. This can be seen in FIGS. 1, 2 and 3.

In accordance with my invention, each of the interrupters is supported at only one of its ends, the opposite end of the interrupter being unsupported except through the supporting structure at said one end. In FIGS. 3-5, for example, this support is located at the right hand end only of each interrupter. The support comprises a pair of pedestal-type insulators 86 disposed generally perpendicular to each other. One of these insulators 86 has its outer end secured to frame member 80, and the other insulator 86 has its outer end secured to frame 80a. At the inner end of the insulators 86, there is a metal bracket 88b of box form secured to both insulators 86 and to the end cap 69 of the vacuum interrupter, thereby supporting the vacuum interrupter on the insulators 86 through the metal bracket 88b. Suitable screws 92 are provided for clamping t8h6e bracket 88b to the usual end fixtures 90 on insulators Referring to FIG. 4, the left-hand end of the interrupter is unsupported except through the above-described insulating support at the right hand end of the interrupter. There is a conductive member 88a secured to the left hand end of the interrupter through which electrical connection is made to stationary contact rod 70; but this member 88a includes flexible conductive braid 880 which prevents the member 88a from imparting any significant support to the left hand end of the interrupter. Conductive member 88a is split at its upper end to receive the projecting outer end of stationary contact rod 70 and is suitably clamped thereto by a screw 89. At its lower end, the conductive member 88a is clamped to the usual end fixture 90 of a pedestal insulator 93. The pedestal insulator 93 is suitably fastened at its outer end to the adjacent frame member 80, as shown in FIG. 3.

For carrying current to and from each interrupter, a pair of spaced-apart horizontally-extending conductive studs 95 and 96 are provided at opposite ends of each interrupter 60. As best shown in FIG. 1, the studs 95 and 96 carry at their free ends the previously-mentioned sockettype disconnect contacts 57 that mate with stationary contacts 55. The disconnect contacts 57 can be of any suitable conventional form and will therefore not be described in detail in the present application. Reference may be had to the aforesaid Darrow et al application if more details are desired. It is believed sufficient for the present to say that each of the plug-type disconnect contacts 55 is positioned to enter its associated socket disconnect contact 57 when the movable circuit breaker unit is fully inserted.

The opposite end of each of the studs 95 or 96 is supported generally rigidly on an associated one of the pedestal insulators 86 or 93, as the case may be. As shown in FIGS. 4 and 5, the right hand stud 95 is bolted between bracket 88b and the right hand pedestal insulator 86 by screws 92. The left hand stud 96 is suitably bolted by screws 91 to the other pedestal insulator 93. A conductive spacer 97 that is clamped between stud 96 and conductive member 88a carries current between these parts and appropriately locates the stud 96. It will be noted that the insulator 93 supports stud 96 on framework 80, 28 independently of any support from the envelope-supporting structure 88b at the right hand end of the envelope 62.

Current is conducted between stud 95 and movable contact rod 76 by means of flexible metal braid 98 suitably attached at one end to stud 95 and at its other end to movable contact rod 76. Flexible braid 98 permits contact rod 76 to move without affecting the connection between parts 76 and 95. Assuming that the movable circuit breaker unit is in its connected position and the vacuum interrupters 60 are closed, current in each phase can flow serially through the following parts, best shown in FIG. 4: stud 95, braid 98, contact rod 76, contacts 66, 64, contact rod 70, conductive member 8811, spacer 97, and stud 96.

For producing circuit-opening and circuit-closing movement of the contact rods 76 of the three interrupters, a contact-operating machanism 120 (shown in FIG. 3) is provided adjacent the front panel 110 of the movable circuit breaker unit. This contact-operating mechanism can be of any suitable conventlonal construction, and since its details form no part of the present invention, it is shown in block form only. Mechanism 120 is supported on frame members 83 of truck 26 at a location that is approximately in vertical alignment with the center vacuum interrupter 60.

For transmitting forces between operating mechanism 120 and interrupters 60, a vertically-extending rotatable actuating shaft 125 (shown in FIG. 3) is provided. This actuating shaft 125 is located near the front of the truck 26 at one side thereof and extends in a vertical direction from the level of the mechanism 120 to the levels of the upper and lower interrupters 60. The actuating shaft 125 is journaled in suitable stationary bearings (not 6 shown) provided on braces 82. As shown in FIG. 3, the operating mechanism comprises an output arm 126 that is pivotally connected to the rotatable shaft through a crank 127 that is suitably fixed to the shaft. When the operating mechanism operates, it effects rotation of the shaft 125 through these parts 126 and 127.

At the level of each interrupter, there is an operating crank 130 that is also fixed to the actuating shaft 125. Each of these three operating cranks 130 is coupled to the movable contact rod of an.associated interrupter through an insulating operating rod 132, shown in FIGS. 1, 3, and 5. Each of these insulating operating rods 132 is pivotally connected at one end of the free end of an associated crank 130 and is operatively connected at its other end to the contact rod 76. When the actuating shaft 125 is rotated in a clockwise direction from its position of FIG. 3, it simultaneously drives the operating rods 132 in the direction of the arrow 152 in FIG. 3 to produce substantially simultaneous closing of the interrupters. When actuating shaft 125 is driven in a reverse direction from its closed position, it simultaneously pulls the operating rods 132 in a direction opposite to the arrow 152, thereby simultaneously opening the three 1nterrupters.

For connecting each of the operating rods 132 to its associated movable contact rod 76, there is provided force-transmitting means 140, which can best be seen 1n FIG. 5. A basic purpose of this force transmitting means is to convert longitudinal motion of the operatlng rod 132 into longitudinal motion of the contact rod 76. Another purpose of the force-transmitting means 140 1s to provide contact-wipe at the end of a closing operation, as will soon be explained. The force-transm1tt1ng means 140 is substantially the same as that claimed and disclosed at 100 in Pat. 3,163,735-Miller, assigned to the asslgnee of the present invention, and reference may be had to that patent if a more detailed explanation is desired. In general, this force-transmitting means 140 comprlses a guide link 141 that is pivotally supported at one end on a stationary pivot 142 and is pivotally connected at 1ts opposite end to the operating rod 132 by means of a pivot 144. The force-transmitting means 140 further comprises an intermediate link 146 of rod form that IS pivotally connected at one end to the contact rod 76 and 1s pivotally connected with lost motion at its opposite end to the operating rod 132. The connection to the contact rod is through pivot 147, and the connection to the operating rod is through the previously-described pivot 144, which is carried by the operating rod 132 and 1s journaled in the operating rod 132 for rotation relative to the operating rod. This latter pivot 144 has a transversely-extending hole therethrough which slidably receives the intermediate rod 146 to permit motion of pivot 144 along the length of intermediate rod 146. Disposed between pivot 144 and the other end of the lntermediate rod 146 is a compression spring 150 that encircles the intermediate rod 146. This compression spring 150 tends to urge the pivot 144 against the stop 151 fixed to the intermediate rod 146. Since the compression spring 150 is carried by the intermediate rod 146, it will be apparent that the spring moves bodily with the intermediate rod during all interrupter operations.

When the operating rod 132 is driven in the direction of arrow 152 to initiate a circuit breaker-closing operation, driving forces are transmitted through the compression spring 150 to force the contact rod 76 to the left, thereby moving contact 66 into engagement with contact 64. Following this engagement, operating rod 132 continues moving in the direction of arrow 152, forcing pivot 144 to slide along the intermediate rod 146, compressing spring 150, and opening a space between the pivot 1'44 and stop 151. This overtravel action during which the spring 150 is compressed serves primarily to provide contact-wipe. More specifically, this action assures that the contacts 66, 64 are firmly driven into engagement despite loss of contact material through wear and arc-erosion and without blocking the contacts of the other interrupters from engaging should the contacts of one of the interrupters engage ahead of the contacts of the other interrupters. Corresponding spring couplings are provided on the other interrupters to compensate for contact wear and arc-erosion in these interrupters and permit the contacts of the illustrated interrupter to be driven into engagement should the contacts of the other inerrupters engage first. Because of the role it plays in providing contact-wipe, the force-transmitting means 140 is also referred to as contact-wipe mechanism.

For insuring straight line motion of the contact rod 76 during the above-described closing operation, a slide bearing 160 is provided about contact rod 76. This slide bearing 160 is suitably fixed to the stationary bracket 88b. Additional guide means (not shown) may be provided, if desired, to aid the slide bearing 160 in producing straight line motion of the contact rod 76.

Contact-opening is effected by driving the operating rod 132 back to its position of FIG. in a direction opposite to the arrow 152. During initial movement of the operating rod in this direction, no opening force is applied to the movable contact rod 76 since the pivot 144 is merely sliding along the intermediate rod 146 without driving the intermediate rod. This lost motion continues until the pivot 144 strikes stop 151. When this occurs, an abrupt opening force is applied to the movable contact 66, and it separates at high speed from contact 64 to produce interruption of the circuit, as previously described.

In the circuit breaker illustrated in the aforesaid Darrow et al. application, each of the vacuum interrupters is supported on insulators at both of its ends. In Working with a circuit breaker of that design, I found that when the closing force applied through rod 132 was made relatively high, e.g., over 600" pounds, the life of the interrupter was seriously shortened. The high closing forces were imposing severe loads on the end caps 68 and 69 of the interrupter. After a relatively small number of operations, the severe loads on the end caps were found to cause a failure of the Weld joint or seal at 73.

After an intensive search for a solution to this problem, I have found a relatively simple way of protecting the envelope against these failures. This involves eliminating the relatively rigid support for the interrupter heretofore envelope present at its left hand (or stationary-contact) end and leaving the envelope unsupported at this end except through the support at its opposite end. The conducting means 88a at the left hand end of the interrupter includes flexible braid 88c and is therefore incapable of imparting support to this end of the interrupter envelope. The left hand insulator 93 is now relied upon merely to support the stud 96 and not the interrupter 60. With the support thus modified, I have been able to extend the life of the interrupter through approximately twenty times the number of closing operations previously capable of being handled by the interrupter.

It appears that if the interrupter envelope is supported generally rigidly at both ends, the closing force that is transmitted to bracket 88b tends to load the interrupter envelope 62 in bending. This closing force is imparted to the bracket 88b via a line of action extending along the axis of operating rod 132 and therefore transverse to the longitudinal axis of the interrupter envelope. This high force will produce a certain amount of deflection of the support at the right hand (or movable-contact) end of the interrupter and will thus slightly displace the right hand end of the envelope. This displacement will impose large bending forces on the envelope and damaging forces on seals 73 if the left hand (or stationary-contact) end of the envelope is restrained, but virtually none, I have found, if left unrestrained. When the stationary contact end of the envelope is unrestrained, as in my illustrated arrangement, displacement at the movable-contact end Wlll be resisted substantially entirely by the support structure at the right hand end of the envelope rather than by restraining fo transmitted through the envelope.

It is important that the right hand (or movable-contact) end of the illustrated interrupter envelope be supported with considerable rigidity. This is so because the deflection occurring at the right hand end of the envelope must be kept low enough to prevent the braids 880 from imposing any significant restraint on the left hand end of the envelope when it moves slightly in response to deflection on the support atthe right hand end of the envelope. Another reason for supporting the right hand end of the envelope with considerable rigidity is that deflection at the right-hand end undesirably decreases the amount of wipe that is made available by wipe mechanism on closing.

For these reasons, I use two spaced-apart insulators 86 substantially normal to each other at the right hand end of the envelope to impart extra rigidity to the support, thus minimizing the deflections produced by closing forces.

While I have shown and described a particular em bodiment of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from my invention in its broader aspects; and I, therefore, intend in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A vacuum-type circuit breaker comprising:

(a) a framework,

(b) a vacuum interrupter comprising a generally tubular envelope at least partially of insulating material and conducting means forming a conductive path through said tubular envelope when the interrupter is closed, said conducting means comprising a pair of separable contacts and a conductive rod fixed to one of said contacts and longitudinal movable along the longitudinal axis of said tubular envelope through one end of said envelope,

(c) means for mounting said interrupter on said framework comprising (l) supporting structure fixed to said one end of said tubular envelope and (2) first insulating structure fixed to said supporting structure and to said framework for substantially rigidly securing said one end of the tubular envelope to said framework,

(d) the other end of said tubular envelope being substantially unsupported except through said first insulting structure at said one end,

(e) means acting during circuit-breaker closing to exert on said supporting structure a substantial force acting in a direction transverse to said longitudinal axis of said tubular envelope comprising contactoperating means coupled to said rod, supported on said supporting structure, and extending from said supporting structure via a path disposed transverse to said longitudinal axis,

(f) a conductive stud at said other end of said tubular envelope projecting from said envelope,

( connecting means for electrically connecting said stud and said conducting means in the associated vacuum interrupter in series comprising a flexible connection between said stud and the portion of said conducting means at the other end of said tubular envelope,

(h) and second insulating structure for supporting said stud on said framework independently of support from said supporting structure at said one end of the envelope.

2. A circuit breaker as defined in comprising:

(a) a second stud connected in series with said conducting means, located at said one end of said interrupter, and projecting from said envelope transversely of said longitudinal axis, and

claim 1 and further (b) means for substantially rigidly connecting said stud to said one end of said tubular envelope and for supporting said stud on said framework through said first insulating structure.

3. The circuit breaker of claim 1 in which said transversely-acting force exerted by said contact-operating means is of a magnitude sufiicient to cause damage to said envelope if said other end of the envelope is rigidly attached to said second insulating structure.

4. The circuit breaker of claim 1 in which said first insulating structure comprises a pair of pedestal type insulators disposed generally perpendicular to each other, the insulators each having one end fixed to said framework and an opposite end fixed to said supporting structure.

5. A circuit breaker as defined in claim 1 and further comprising:

(a) a second stud connected in series with said conducting means, located at said one end of said interrupter, and projecting from said envelope transversely of said longitudinal axis, and

(b) disconnect contacts at the free ends of said studs for carrying current to and from said studs.

6. The circuit breaker of claim 1 in which:

(a) additional vacuum interrupters constructed as in 25 (b) a pair of studs is provided for each additional vacuum interrupter at opposite ends of its envelope, (0) connecting means is provided for electrically connecting the studs of each of said additional vacuum interrupters in series with the conducting means extending through its envelope, said connecting means comprising a flexible connection between the portion of said conducting means at said unsupported end of said envelope and the associated adjacent stud, (d) and insulating structure for supporting each of the studs at said unsupported end of each envelope on said framework independently of support from said supporting structure at said one end of said envelope.

References Cited UNITED STATES PATENTS 2,480,622 8/ 1949 Warnock 200 -144 X 3,280,282 10/1-966 Rodeseike 200144 X 3,345,484 10/1967 Polinko 200-144 3,397,293 8/1968 Darrow 20050 3,404,247 10/ 1968 Glassanos 200144 3,418,439 12/1968 Casey- 200-144 LARAMIE E. ASKIN, Primary Examiner G. P. TOLIN, Assistant Examiner US. Cl. X.R. 317103 

